static class Dumper
    {
        public static string Dump(Node root)
        {
            var sb = new StringBuilder();
            foreach (var line in dump(root))
                sb.AppendLine(line);
            return sb.ToString();
        }

        static private IEnumerable<string> dump(Node root)
        {
            yield return root.Text;
            if (root.Children.Count == 0)
                yield break;
            for (int i = 0; i < root.Children.Count; i++)
            {
                bool firstLineOfChild = true;
                bool lastChild = i == root.Children.Count - 1;
                foreach (var line in dump(root.Children[i]))
                {
                    string prefix = lastChild
                        ? (firstLineOfChild ? "└─" : "  ")
                        : (firstLineOfChild ? "├─" : "│ ");
                    yield return prefix + line;
                    firstLineOfChild = false;
                }
            }
        }
    }